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Psoriasis
Image Notes: A young man whose back and arms are affected by psoriasis.
Psoriasis is a disease which affects the skin and joints. It commonly causes red scaly patches to appear on the skin. The scaly patches caused by psoriasis, called psoriatic plaques, are areas of inflammation and excessive skin production. Skin rapidly accumulates at these sites and takes a silvery-white appearance. Plaques frequently occur on the skin of the elbows and knees, but can affect any area including the scalp and genitals. Psoriasis is hypothesized to be immune-mediated and is not contagious.
The disorder is a chronic recurring condition which varies in severity from minor localised patches to complete body coverage. Fingernails and toenails are frequently affected (psoriatic nail dystrophy) - and can be seen as an isolated finding. Psoriasis can also cause inflammation of the joints, which is known as psoriatic arthritis. Ten to fifteen percent of people with psoriasis have psoriatic arthritis.
The cause of psoriasis is not known, but it is believed to have a genetic component. Several factors are thought to aggravate psoriasis. These include stress, excessive alcohol consumption, and smoking. Individuals with psoriasis may suffer from depression and loss of self-esteem. As such, quality of life is an important factor in evaluating the severity of the disease. There are many treatments available but because of its chronic recurrent nature psoriasis is a challenge to treat.
History
Psoriasis is probably one of the longest known illnesses of humans and simultaneously one of the most misunderstood. Some scholars believe psoriasis to have been included among the skin conditions called tzaraat in the Bible. In more recent times psoriasis was frequently described as a variety of leprosy. The Greeks used the term lepra (?????) for scaly skin conditions. They used the term psora to describe itchy skin conditions. It became known as Willan's lepra in the late 18th century when English dermatologists Robert Willan and Thomas Bateman differentiated it from other skin diseases. They assigned names to the condition based on the appearance of lesions. Willan identified two categories: leprosa graecorum and psora leprosa.
While it may have been visually, and later semantically, confused with leprosy it was not until 1841 that the condition was finally given the name psoriasis by the Viennese dermatologist Ferdinand von Hebra. The name is derived from the Greek word psora which means to itch.
It was during the 20th century that psoriasis was further differentiated into specific types.
Types of psoriasis
The symptoms of psoriasis can manifest in a variety of forms. Variants include plaque, pustular, guttate and flexural psoriasis. This section describes each type (with ICD-10 code.
Plaque psoriasis (psoriasis vulgaris) (L40.0) is the most common form of psoriasis. It affects 80 to 90% of people with psoriasis. Plaque psoriasis typically appears as raised areas of inflamed skin covered with silvery white scaly skin. These areas are called plaques.
Flexural psoriasis (inverse psoriasis) (L40.83-4) appears as smooth inflamed patches of skin. It occurs in skin folds, particularly around the genitals (between the thigh and groin), the armpits, under an overweight stomach (pannus), and under the breasts (inframammary fold). It is aggravated by friction and sweat, and is vulnerable to fungal infections.
Guttate psoriasis (L40.4) is characterized by numerous small oval (teardrop-shaped) spots. These numerous spots of psoriasis appear over large areas of the body, such as the trunk, limbs, and scalp. Guttate psoriasis is associated with streptococcal throat infection.
Pustular psoriasis (L40.1-3, L40.82) appears as raised bumps that are filled with non-infectious pus (pustules). The skin under and surrounding pustules is red and tender. Pustular psoriasis can be localised, commonly to the hands and feet (palmoplantar pustulosis), or generalised with widespread patches occurring randomly on any part of the body.
Nail psoriasis (L40.86) produces a variety of changes in the appearance of finger and toe nails. These changes include discolouring under the nail plate, pitting of the nails, lines going across the nails, thickening of the skin under the nail, and the loosening (onycholysis) and crumbling of the nail.
Psoriatic arthritis (L40.5) involves joint and connective tissue inflammation. Psoriatic arthritis can affect any joint but is most common in the joints of the fingers and toes. This can result in a sausage-shaped swelling of the fingers and toes known as dactylitis. Psoriatic arthritis can also affect the hips, knees and spine (spondylitis). About 10-15% of people who have psoriasis also have psoriatic arthritis.
Erythrodermic psoriasis (L40.85) involves the widespread inflammation and exfoliation of the skin over most of the body surface. It may be accompanied by severe itching, swelling and pain. It is often the result of an exacerbation of unstable plaque psoriasis, particularly following the abrupt withdrawal of systemic treatment. This form of psoriasis can be fatal, as the extreme inflammation and exfoliation disrupt the body's ability to regulate temperature and for the skin to perform barrier functions.
Text and images are licensed under the GNU Free Documentation License. Material is used from the Wikipedia article "Psoriasis".
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